Convert moles to grams or grams to moles using molar mass, with worked chemistry examples and a reverse mode for quick checks.
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Convert moles to grams using molar mass Enter the mole amount and the compound's molar mass to convert between moles and grams. The same calculator also works in reverse when you already know the mass and need the amount in moles.
Direction
Formula
grams = moles × molar mass
This page stays narrow on purpose: it translates an already-known mole or mass value using the molar mass you supply. If you need to derive the molar mass first, use the molecular-weight calculator.
Result
36.03 g
2 mol × 18.02 g/mol = 36.03 g
Moles
2 mol
Grams
36.03 g
Molar mass
18.02 g/mol
Mode check
The calculator multiplies your mole amount by the molar mass to get grams.
Moles to grams calculator: turn mole amounts into grams using molar mass
Use this moles to grams calculator when you already know the amount of substance in moles and want the mass in grams. The same page also works in reverse for grams to moles checks, because both directions depend on the same molar mass value.
The moles to grams formula
Mass in grams equals the number of moles multiplied by the molar mass. If a substance has a molar mass of 18.015 g/mol, then 2 moles of that substance weigh 36.03 grams.
The reverse calculation is just as simple: grams divided by molar mass gives moles. That is why this page is useful for both moles to grams and grams to moles checks.
grams = moles × molar mass
Use this when you know the mole amount and need mass.
moles = grams ÷ molar mass
Use this when you know the mass and need the amount in moles.
Why molar mass matters
One mole of different substances does not weigh the same amount, so you cannot convert moles to grams without molar mass. Water, sodium chloride, calcium hydroxide, and glucose all have different molar masses even though they are all measured in moles.
If you already know the chemical formula but not the molar mass, use a molecular-weight calculator first. Once you have the molar mass, this converter can translate the mole amount into grams or move the other way back to moles.
Further reading
Molecular weight calculator — Calculate molar mass from a chemical formula before converting between moles and grams.
If you have 2 moles of water and water's molar mass is 18.015 g/mol, the mass is 36.03 g. If you have 0.25 moles of carbon dioxide at 44.01 g/mol, the mass is 11.00 g. Those are the kinds of quick checks this page is built for.
The reverse direction works too. If you have 36.03 g of water, divide by 18.015 g/mol to recover 2 moles. If you have 5.00 g of sodium chloride at 58.44 g/mol, the amount is about 0.0855 mol.
How this converter fits into chemistry work
This page is a narrow chemistry helper. It does not infer molar mass from a formula, and it does not turn mass into particle count or solution concentration. That keeps the result clean and avoids mixing in extra assumptions that belong to a different calculator.
The tool is still useful in lab homework, stoichiometry checks, recipe-style preparation steps, and quick classroom problem solving. It gives you a fast bridge between the mole count and the mass you need to weigh.
Molarity calculator — Use this when the real question is solution concentration instead of mass.
When to use a different calculator
Use a molecular-weight calculator when the formula is known but the molar mass is not. Use a grams-to-moles calculator when grams are the starting point and you want the mole amount. Use a molarity calculator when the problem involves solution volume and concentration instead of pure-substance mass.
Keeping those workflows separate reduces errors. A mole is a counting unit, while grams are a mass unit, so the extra step between them is always the molar mass.
Frequently asked questions
What is the formula for moles to grams?
The formula is grams = moles × molar mass. If the substance has a molar mass of 18.015 g/mol, then 2 moles equal 36.03 grams.
How many grams is 2 moles of water?
Two moles of water weigh 36.03 grams because water's molar mass is 18.015 g/mol. Multiply 2 by 18.015 to get the answer.
How do I convert grams back to moles?
Divide the mass in grams by the molar mass. For example, 36.03 g of water divided by 18.015 g/mol gives 2 moles.
Why do I need molar mass?
Because one mole of different substances has different masses. Molar mass tells you how many grams correspond to one mole of the specific compound or element you are working with.
Is molar mass the same as molecular weight?
They are numerically equivalent for a given substance, but molar mass is expressed in grams per mole while molecular weight is often discussed as a relative or formula-based value. In practical chemistry, the molar mass is the number you use for this conversion.
Can I use this for elements as well as compounds?
Yes. An element still has a molar mass, so the same formula works. The only requirement is that you know the correct molar mass for the element or compound.
What if I only know the chemical formula?
Calculate the molar mass first, then come back to this converter. A molecular-weight calculator is the right tool for formula parsing and molar-mass lookup.
Why does the calculator have a reverse mode?
Because the same molar mass links both directions. If you know grams, dividing by molar mass gives moles; if you know moles, multiplying by molar mass gives grams.
Does this work for impure samples?
It works mathematically, but the answer only describes the total sample mass if you assume the sample behaves like the pure substance you entered. For mixtures or impure samples, the chemical interpretation changes.
When should I use a different chemistry calculator?
Use a molecular-weight calculator when the formula is unknown, a grams-to-moles calculator when grams are the input, and a molarity calculator when solution concentration and volume matter.
